Short of a NV4500, the SM465 is going to be just about bullet proof. They're not perfect, and my 455 will probably tear it up sooner than a NV4500. You can't beat them for the money... and I got a good deal on mine. I got the tranny, t-case and cross-member for $250.

IMHO, spacers DO NOT count as a true suspension lift. You only gain a small amount of clearance and you're still left w/ just about the same articulation too. For the money, a body lift of the same height will net you more benefits than spacers of the same thickness.